Large amounts of byproducts are generated by the food processing industries in the 21st century including bioactive compounds such as polysaccharides, polyphenols, carotenoids, and dietary fiber. Due to a lack of sustainable extraction techniques, these processing wastes are regarded as having negligible value in comparison to processed fruit or vegetables. Conventional extraction has limitations in terms of time, energy, and solvent usage. In comparison with conventional methods of extraction, ultrasonic-assisted extraction can extract bioactive components in a short period, at low temperatures, and with less energy and solvent, as well as maintaining the functionality of the components. However, UAE-related variables such as frequency, power, duty cycle, temperature, time, solvent type, and liquid-solid ratio must be understood and optimized for each byproduct. This article provides the mechanism, concept, and factors that influence bioactive compound extraction, with a focus on tomatoes.